The present application claims priority upon Japanese Patent Application No. 2001-30192 filed on Nov. 6, 2001, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a method of controlling carrying of recording paper, a recording apparatus and a recording method.
Furthermore, the present invention relates to a recording apparatus that is provided with recording execution means for executing recording on a recording paper that has been supplied to a recording execution area, and recording paper carrying means for intermittently carrying the recording paper in the paper-feed direction by rotating a carry driving roller that is driven by a rotation driving power source.
2. Description of the Related Art
As an example of recording paper carrying means for carrying the recording paper by a predetermined carrying amount in the paper-feed direction, means using a carry driving roller that is rotated by a rotation driving power source, such as a stepping motor, is common. The recording paper is pressed and tightly adheres against the outer circumferential surface of the carry driving roller by, for example, driven rollers having biasing means, and the recording paper is carried in the paper-feed direction by the rotation of the carry driving roller. A high-friction resistance coating having fine protrusions and depressions is formed on the outer circumferential surface of the carry driving roller, and due to its friction resistance, the recording paper adheres tightly to the outer circumferential surface of the carry driving roller, and the rotation of the carry driving roller is conveyed without loss.
On the other hand, the rotation driving power source of, for example, the stepping motor rotating the carry driving roller is rotated under control by a recording controller. The recording controller takes-in a signal that is output by means for detecting a rotation amount of the carry driving roller, and when it is detected that the carry driving roller has rotated for an amount corresponding to a predetermined carrying amount, then the controller controls the rotation driving power source so that it stop. This means for detecting the rotation amount of the carry driving roller can be realized by a variety of means, and one example of a conventionally known means is means that detects the rotation amount of the carry driving roller by detecting slits that are formed at equal intervals in a rotor which rotates unitarily with the carry driving roller.
The means for detecting the rotation amount is configured by a rotor that is arranged on a rotation shaft of the carry driving roller and provided with slits at equal intervals serving as targets for a rotation stop position of the rotation driving power source, and slit detection means with which the slits in the rotor can be detected. Controlling of carrying the recording paper for a predetermined carrying amount is performed by controlling rotation of the rotation driving power source rotate with the means for detecting the rotation amount of the carry driving roller, until the means detects a number of slits that corresponds to the predetermined carrying amount of the recording paper.
The unit carrying amount that corresponds to a minimum carrying amount by the recording paper carrying means is the length obtained by dividing the outer circumference of the carry driving roller, that is, the circumference of the outer surface of the carry driving roller, by the total number of slits formed in the rotor. That is to say, the length of the outer circumference of the carry driving roller that corresponds to the slit interval of the slits, which are formed at equal intervals, is the unit carrying amount of the recording paper. Consequently, when carrying the recording paper for a predetermined recording paper carrying amount, first, that predetermined recording paper carrying amount is divided by the unit carrying amount, and to calculate to how many unit carrying amounts this carrying amount corresponds. Subsequently, the rotation driving power source is rotated under control, thus rotating the carry driving roller, until the means has detected this number of slits. Then, when this number of slits has been detected, the rotation driving power source is stopped, thus stopping the carry driving roller.
However, if the recording paper carrying amount supposed to be carried is a carrying amount that cannot be divided out by the unit carrying amount, then the remainder carrying amount that could not be divided out is either rounded down or rounded up, and the recording paper has to be carried with the rounded carrying amount. Thus, a carrying error corresponding to the remainder carrying amount that has been rounded down or rounded up will be accumulated at each carrying step.
Conventionally, shifts in the carrying amount caused by the accumulation of this carrying error due to rounding were not that large to lead to a particularly large decrease in the recording quality, and were not perceived as a big problem.
However, as the image quality of recording apparatuses has increased in recent years, a higher precision is needed for the carrying precision of the carry driving roller, and shifts in the carrying amount due to rounding cannot be ignored anymore. And it can be said that it is already not possible to meet the improvement in image quality of recording apparatuses of recent years with the simple way of carrying of recording paper according to slit units, which are dependent on the precision of the outer diameter of the carry driving roller.
Furthermore, since there are of course variations within the manufacturing tolerances for the outer diameter of the carry driving roller, the carrying error of the recording paper caused by these variations decreases the carrying precision of the carry driving roller. In order to address this, these variations can be reduced by increasing the precision during manufacturing, but this will lead to an increase in manufacturing costs.
By the way, an example of a conventional technology for carrying the recording paper with high precision without necessitating component precision for all components, such as the carry driving roller, has been disclosed in JP H11-49399A.
In this configuration, the carrying amount of the recording paper is controlled by driving, under control, the carry driving roller by a pulse motor, outputting a number of pulses corresponding to the recording paper carrying amount from the pulse motor, and counting the number of pulses output by the pulse motor to control the rotation amount of the carry driving roller. Moreover, a specific rotation reference position is provided on the rotation shaft of the carry driving roller, a periodic fluctuation error of the rotation period of the carry driving roller is calculated from the rotation reference position detected with means for detecting the rotation reference position and the number of pulses output by the pulse motor, and a control for correcting the carrying amount shift caused by this periodic fluctuation error is executed at every rotation reference position. Furthermore, upon correcting the shift of the carrying amount of the recording paper at every rotation reference position, the correction is performed by referring to a correction value table in which correction values for every rotation reference position are stored.
However, this conventional technology disclosed in the above-mentioned publication corrects carrying amount shifts that are caused by periodic fluctuation errors in the carry driving roller, but it does not correct carrying amount shifts caused by the outer diameter precision of the carry driving roller. Consequently, means for detecting the periodic fluctuation error at a specific rotation reference position is necessary, the correction of the carrying amount can be carried out only at a specific rotation reference position, and the shift of the carrying amount cannot be corrected at every carrying step. Consequently, tiny shifts in the carrying amount at every carrying step that are caused due to the precision of the outer diameter the carry driving roller cannot be corrected, so that there seems to be a limit for carrying the recording paper with ever higher precision.
Furthermore, when trying to increase the precision of the correction, the data table necessarily becomes bigger, and an accordingly larger storage medium is needed to store the data table. Consequently, there is the possibility that the problem occurs that low-capacity storage media installed in storage apparatuses of the low price bracket cannot handle such circumstances.
The present invention has been contrived in view of such a situation, and one object thereof is to realize a further improvement in quality of a recording image.
It is a further object of the present invention to realize a further improvement of the recording image quality with a low-cost recording apparatus while keeping the outer diameter precision of the carry driving roller by a control of the carry of recording paper which gives rise to only small shifts in the recording paper carrying amount and which does not depend on the outer diameter precision of the carry driving roller.
It is a further object of the present invention to realize a recording method having the following steps:
carrying the recording paper for a predetermined amount, based on a first carrying amount for which the recording paper is to be carried;
executing recording on the recording paper that has been carried for the predetermined amount;
executing an addition process of adding an amount obtained by subtracting the predetermined amount from the first carrying amount to a second carrying amount for which the recording paper is to be carried; and
carrying the recording paper based on the second carrying amount to which the addition process has been executed.
Features and objects of the present invention other than the above will become clear by reading the description of the present specification with reference to the accompanying drawings.